The present invention relates generally to molding apparatus and more particularly to a system for handling pattern devices in a molding plant for the production of mold halves in mold boxes. More particularly the invention relates to a system utilizing a swingable transfer device which is provided with two diametrically opposed tables which are moveable between a waiting position and an operating position, with a conveyor track comprising the table which is in the waiting position extending toward opposite sides of the waiting position.
An arrangement of the type above-mentioned is known from German Offenlegungsschrift 28 22 028. Arrangements of this type applied in a molding plant which has a molding station, make it possible to alternatingly provide two pattern devices, for example, for an upper mold part and for a lower mold part. While a molding operation is performed upon that pattern device which has been positioned by means of the table in the operating position, it is possible to perform operations, such as cleaning or applying a cooling iron which rests on the table which is in the waiting position. Furthermore, it is also possible to replace pattern devices on the tables with pattern devices which are on the conveyor track. That pattern device which rests on the table which is in the waiting position can always be moved toward one side of the conveyor track and a new pattern device can be moved onto the table from the opposite side of the conveyor track. Since it is possible to repeat this procedure when the other of the two tables of the transfer device reaches the waiting position the next time, it is possible to exchange pairs of pattern devices without changing the cycle time of the molding plant.
When a foundry which is not intended for production of a single uniform casting must operate with only a single molding machine, this known arrangement has been found not to meet the operating requirements. As is well known, all divisions of a foundry should be capable of operating with as constant an output as possible if optimum results are to be achieved with respect to quality and efficiency. For example, the requirements of molten metal for the foundry should be constant in order to also enable operation of the smeltery with a constant output. Since the requirement for different types of molten metal may vary, variations in the requirements of molten metal for the foundry can be compensated only by bringing the average requirement of the cast molds to an approximately constant value. This is achieved by casting molds with above average molten metal requirements in addition to molds with below average molten metal requirements. Accordingly, the molding plant may be made capable of delivering different molds in a regular sequence.
Similar considerations to those raised above with respect to the requirement of molten metal also apply, for example, to the requirement of cores and the time requirement for cleaning the castings. However, by means of the known device it is not possible to provide the molding plant with the pattern devices in such a manner that variations in the aforementioned factors can be compensated by an appropriately adjusted mold production.
Accordingly, the present invention is directed toward providing an arrangement for handling pattern devices in molding plant with more than two pattern devices, while maintaining the cycle time and predetermined constant sequence.